Waste treatment system

ABSTRACT

A waste treatment system may include a liquid separator for removing water from solid waste, a mixing tank connected to the liquid separator for mixing the solid waste with an oxidizing agent, a heat exchanger connected to the mixing tank for collecting heat generated by an exothermic reaction caused by mixing the oxidizing agent with the solid waste, and a sanitizer connected to the liquid separator to sanitize the water removed from the solid waste. A waste treatment method may involve separating water from solid waste in a liquid separator, mixing the solid waste from the liquid separator with an oxidizing agent in a mixing tank connected to the liquid separator to cause an exothermic reaction, collecting heat from the exothermic reaction in a heat exchanger coupled with the mixing tank, and sanitizing the water from the liquid separator in a sanitizer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/480,868, filed Apr. 6, 2017, which is a divisionof U.S. patent application Ser. No. 14/255,764, filed Apr. 17, 2014, nowU.S. Pat. No. 9,908,797, entitled, “WASTE TREATMENT SYSTEM.” Thedisclosure of this priority application is hereby incorporated byreference in its entirety into the present application.

FIELD

The present application relates to waste management systems and methods.More specifically, the application relates to waste treatment systemsand methods using an oxidizing agent.

BACKGROUND

Two significant challenges in urban development are processing human andanimal waste and providing adequate supplies of usable water. Treatmentof waste, or “wastewater,” in urban environments, such as commercial andresidential buildings, is a specific challenge. Wastewater is typicallyreferred two in two classes—greywater and blackwater. Greywater, or“sullage,” is defined as wastewater generated from sinks, showers,baths, laundry, dishwashers and the like, which can be recycled on-sitefor uses such as toilet flushing, landscape irrigation and constructedwetlands. Blackwater refers to the discharge from toilets—i.e., watercontaining human waste. In commercial and residential buildings,grey-water and black-water are removed together, using a shared sewagesystem, to be treated at centralized waste treatment plants, beforebeing returned to the environment at large. With anticipated increasesin population and associated waste generation, waste management becomesone of the most critical aspects of sustainable development.

At the same time, there is a critical need to provide more and morepotable water for urban growth. Many urban areas struggle to find enoughwater for the needs of their residents. Significant water conservationwill be required to preserve freshwater to offset the limited supply andrising cost of potable water resources.

India provides just one example of the increasing need for wastewatermanagement and potable water. India is the second largest country in theworld, with a population of over 1.2 billion. It has one of the fastestgrowing economies in the world, recording over 896% growth over the lastthree years. Despite, or in some cases because of, this explosivegrowth, a large percentage of the Indian population still does not haveaccess to safe water. On one hand, the pressures of development arechanging the distribution of water in the country. On the other hand,access to adequate water has been cited as the primary factorresponsible for limiting development. Only about half of the cities inIndia are supplied with piped water. For cities that have a populationof between one and five million, their municipal authorities distributewater for only a few hours per day. The few hours that water isavailable, inadequate pipe pressure makes water delivery a struggle.

Meanwhile, the release of untreated wastewater in India has resulted inincreased pollution and depletion of clean water resources. The mostpolluting sources of untreated wastewater are city sewage systems andindustrial waste discharged into rivers. The facilities to treatwastewater are not adequate in any city in India. Presently, only about10% of the waste water generated is treated, while the rest isdischarged as-is into bodies of water.

Human and animal solid waste (feces) is composed of organic matter,which at least in theory could be incinerated or at least sterilized toeliminate bacterial activity and bad odor. A major problem associatedwith fresh feces, however, is their high water content, which inhibitsincineration and unfortunately provides a good medium for bacterialgrowth and propagation. Furthermore, the high water content makes thefeces sticky and dirty. Attempting to burn fresh feces by an externalheat source, such as a gas burner, typically results in formation of anexternal layer of inorganic matter that insulates the wet interior andinhibits heat transfer and combustion thereto. Efficient heat transferto the interior parts of the feces and water evaporation therefrom areessential components of fecal disposal by heat.

Innovators have previously attempted to circumvent this solid wastedisposal challenge by mixing an oxidizing agent (e.g., potassiumpermanganate) with the waste to generate heat within the waste. Thisinnovation is described for use on a small scale, in a pet wastecollection device, in U.S. Pat. No. 8,096,597, which is herebyincorporated by reference in its entirety. No one, however, hasdeveloped a related or similar system or method for use in larger scaleenvironments.

Therefore, it would be advantageous to have improved waste treatmentsystems and methods. Ideally, these systems and methods would providefor efficient treatment of greywater and/or blackwater treatment andwould also conserve water. It would also be ideal if such systems couldbe installed on-site in commercial or residential buildings or in aportable configuration on a truck or other vehicle. At least some ofthese objectives will be met by the embodiments described below.

BRIEF SUMMARY

Systems and methods for treating sewage (or “waste” or “wastewater”) aredescribed herein. Some embodiments are particularly suited for on-siteinstallation and use at large commercial and residential buildings,while other embodiments may be installed on trucks for portable use. Thesystems and methods generally provide for an on-site wastewatertreatment process that addresses two key issues: waste treatment andwater conservation.

The embodiments described herein use commonly available chemicals andhave low maintenance requirements. Various advantages of the embodimentsdescribed herein are: they provides an efficient, cost-effective,on-site sewage treatment system for large commercial and residentialbuildings; they capture usable greywater for toilet flushing; theycapture heat to be used in generating domestic hot water; and theygenerally conserve water and energy.

In one aspect, a waste treatment system may include: a liquid separatorfor removing water from solid waste; a mixing tank connected to theliquid separator for mixing the solid waste with an oxidizing agent; aheat exchanger connected to the mixing tank for collecting heatgenerated by an exothermic reaction caused by mixing the oxidizing agentwith the solid waste; and a sanitizer connected to the liquid separatorto sanitize the water removed from the solid waste. Some embodiments mayalso include a holding tank connected between a sewage system of abuilding and the liquid separator to hold waste from the sewage systembefore directing the waste into the liquid separator.

Some embodiments may further include: a first pipe connecting theholding tank with the liquid separator; a second pipe connecting theliquid separator with the mixing tank; a third pipe connecting theliquid separator with the sanitizer; a fourth pipe leading out of theheat exchanger to carry water heated from the heat exchanger; and afifth pipe leading out of the sanitizer. Optionally, the system mayinclude an emergency bypass channel connected to the building sewagesystem, for diverting the waste to a public sewer system in case offailure of the waste treatment system. The system may also furtherinclude a pump, for pumping the sanitized water toward the building foruse as sanitized greywater.

In various embodiments, the mixing tank may be any suitable commercialmixer, such as but not limited to a high speed mixer, ribbon mixer,plough mixer, conical screw mixer, conical ribbon mixer, double shaftspaddle mixer or continuous mixer. Optionally, some embodiments may alsoinclude a heat source connected to the mixing tank for providing heat tothe solid waste before or during mixing of the solid waste with theoxidizing agent.

The oxidizing agent may be potassium permanganate or any other suitable,safe oxidizing agent. In some embodiments, the system also includes asupply of the oxidizing agent. The system may also optionally include anoxidizing agent container connected to the mixing tank for holding theoxidizing agent before mixing with the solid waste. The system may alsoinclude a heat outflow channel connected to the heat exchanger forallowing the heat generated by the exothermic reaction to be applied toa domestic hot water supply.

In another aspect, a portable wastewater treatment system configured andsized to be placed on a motorized vehicle may include: a sewercollection hose for connecting the wastewater treatment system to asewer system; a sewer pump connected to the sewer collection hose forpumping waste from the sewer into the wastewater treatment system; awastewater holding tank connected to the sewer pump for holding thewastewater; and a mixing tank connected to the wastewater holding tankfor mixing the solid waste with an oxidizing agent. In some embodiments,the system may also include an outflow channel connected to the mixingtank for allowing at least one of processed solid or processed liquid tobe directed out of the mixing tank.

Optionally, the system may further include a liquid separator connectedbetween the holding tank and the mixing tank for separating water fromsolid waste. Such an embodiment may also include a water outflow channelconnected to the liquid separator for allowing the water to flow out ofthe separator. In some embodiments, the system may be sized andconfigured to fit on a back of a truck. In various embodiments, themixing tank may be any suitable commercial mixer, such as but notlimited to those listed above. The system may also include a heatexchanger connected to the mixing tank for receiving and collecting heatgenerated from an exothermic reaction caused by mixing the oxidizingagent with the waste. Again, the oxidizing agent may be potassiumpermanganate, the system may optionally include a supply of theoxidizing agent, and the system may optionally include an oxidizingagent container connected to the mixing tank for holding the oxidizingagent before mixing with the solid waste.

In another aspect, a waste treatment method may involve: separatingwater from solid waste in a liquid separator; mixing the solid wastefrom the liquid separator with an oxidizing agent in a mixing tankconnected to the liquid separator to cause an exothermic reaction;collecting heat from the exothermic reaction in a heat exchanger coupledwith the mixing tank; sanitizing the water from the liquid separator ina sanitizer; and channeling the sanitized water out of the sanitizer.The method may further include, before separating the water from thesolid waste, receiving waste from a building sewer system in at leastone holding tank, and channeling the waste from the at least one holdingtank to the liquid separator.

In one embodiment, the method also involves applying the heat from theheat exchanger to a source of domestic hot water connected to the heatexchanger. The method may also optionally involve channeling thesanitized water into a water system for use as toilet water. In someembodiments, the method also includes collecting processed solid wastefrom the mixing tank in a collection tank. Optionally, the method mayfurther involve providing processed solid waste from the mixing tank foruse as fertilizer.

In some embodiments, the method may further include detecting an problemin a waste treatment system used to perform the method and diverting thewaste from a building sewer system into a public sewer system. In someembodiments, mixing the solid waste with the oxidizing agent involvesmixing the solid waste with potassium permanganate. In some embodiments,the method is performed by a waste treatment system located in or near acommercial or multiple-unit residential building. Alternatively, themethod may be performed by a portable waste treatment system located ona motorized vehicle. In this type of embodiment, the method mayoptionally further involve pumping the wastewater out of a sewer systeminto a holding tank before separating the water from the solid waste.

These and other aspects and embodiments will be described in furtherdetail below, in reference to the attached drawing figures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a system/flow diagram, illustrating an on-site waste treatmentsystem and flow of sewage through the system, according to oneembodiment; and

FIG. 2 is a side view diagram, illustrating a portable waste treatmentsystem for installation and use on a truck, according to anotherembodiment.

DETAILED DESCRIPTION

The various embodiments of a waste treatment system and method describedherein provide for waste treatment with improved efficiency and use ofwater and energy. Some embodiments of the system may be located on-siteat a commercial or residential building, while others may be smallenough to fit on the back of a flatbed truck or other motorized vehicle.The various embodiments involve mixing solid waste with an oxidizingagent to generate heat from an exothermic reaction. In some embodiments,the system collects the generated heat and provides it as usable energy,such as for heating domestic hot water. In some embodiments, the treatedsolid waste may be used as fertilizer. Greywater that is separated fromthe solid waste during the treatment process may be sanitized and usedfor toilets, watering landscaping or other environmentally safe uses.The various embodiments may be used in any of a large number of settingsand locations to provide efficient and effective waste treatment.

The terms “waste,” “wastewater” and “sewage” are sometimes usedinterchangeably in this application. Unless these terms are specificallydescribed as having a particular meaning, they should be interpreted asbeing interchangeable.

Referring to FIG. 1, in one embodiment, a waste treatment system 20 mayinclude one or more holding tanks 3, a liquid separator 4, a mixing tank5, an oxidizing agent 6, a heat exchanger 7, a heated water outflowchannel 8, and a sanitizing tank 10. Holding tank 3 may be connectedwith a building sewer system 1 via one or more connecting pipes 13 andwith liquid separator 4 via one or more other connecting pipes 12.Liquid separator 4 may be coupled with mixing tank 5 via one or moreconnecting pipes 14 and with sanitizer 10 via one or more otherconnecting pipes 16. Heated water outflow channel 8 may be one or morepipes that feed into a domestic hot water storage tank or other form ofdomestic hot water supply. System 20 may also optionally include aliquid outflow channel from sanitizer 10 that is one or more additionalpipes 18. According to various embodiments, multiples of any of thecomponents of system 20 may be provided.

Waste flows into system 20 through the building's sewage system 1. Wateremptying into sewer system 1 from the building comes from sources suchas water closets (WC, or “toilets”), bathtubs (BT, and/or showers), andsinks SK. Other sources may include dishwashers and washing machines,for example. In some embodiments, an emergency bypass 2 may connect withthe building sewer system 1 to allow waste to bypass system 20 if thereis a problem. Typically, this bypass 2 is not part of waste treatmentsystem 20, although in some embodiments, system 20 may include bypass 2or communicate with building sewer system 1 to provide an alert whenthere is a problem, so that waste may be diverted into bypass 2. Afterwaste is processed in mixing tank 5, solid, processed waste 9 may beprovided for use, for example as a fertilizer, or may alternatively bedisposed of as residual waste. Greywater 11 may be pumped out ofsanitizer 10 via a pump 22, which may be part of system 20 or separatefrom system 20. Greywater 11 may then be diverted back to the buildingor elsewhere for use, such as in toilets (WC).

Mixing tank 5 may be any suitable, commercial mixer, such as but notlimited to high speed mixers, ribbon mixers, plough mixers, conicalscrew mixers, conical ribbon mixers, double shafts paddle mixers andcontinuous mixers. In various embodiments, oxidizing agent 6 may beloaded into mixing tank 5 before or after wastewater is passed intomixing tank 5. Heat is generated by mixing the organic waste in mixingtank 5 with a sufficient amount of oxidizing agent 6, which may bepotassium permanganate or any other safe oxidizing agent. In oneembodiment, oxidizing agent 6 may be stored in a compartment orcontainer (not shown) in or connected to mixing tank 5 and dispensedinto mixing tank 5 via one or more valves. Alternatively, oxidizingagent 6 may be manually dispensed into mixing tank 5 from an externalsource before or after waste is dispensed into tank 5. After processing,processed waste 9 may be removed from mixing tank 5, or alternatively,it may be channeled out of mixing tank 5 through a pipe or other meansto a separate solid waste holding tank (not shown).

In addition to providing usable greywater and solid processed waste,system 20 may also provide heat from heat exchanger 7, which may be usedas energy. For example, in one embodiment, heat may be applied to waterand channeled via heated water channel 8 to a domestic hot water supply.

In one method of processing waste using system 20, a main sewage line 1discharges into a holding tank 3 (or multiple holding tanks in someembodiments). Holding tank 3 (or tanks) will typically be designed tomanage peak flows of the sewer to which it is attached. From holdingtank 3, waste is channeled through one or more pipes 12 to liquidseparator 4, which separates liquid from solid waste and thus reducesthe water content of the solid waste to approximately 30% or less.Liquid waste is diverted through pipe(s) 16 to sanitizing tank 10. Solidmatter is transferred through one or more pipes 14 to mixing tank 5.When oxidizing agent (such as potassium permanganate) 6 is mixed withsolid waste, it starts an exothermic reaction, resulting in thegeneration of heat. This reaction may often start quickly, such as inless than one minute or even as quickly as approximately 20 seconds, andmay produce large quantities of heat, such as a temperature of about200° F. The reaction will eventually convert the solid waste material toa dry, odorless, ash-like material. The resulting ash may be used as afertilizer, for example. Tests of resulting ash material from oneembodiment of the method have been conducted, and no phytotoxic signswere observed in a period of 30 days, indicating that the material isenvironmentally safe.

As previously mentioned, liquid separated from the solids is transferredto sanitizing tank 10. After sanitizing, greywater may be pumped throughpipes 18, 11, using pump 22, to supply water closets (WC) with water forflushing and/or to supply greywater for other safe uses.

In one embodiment, system 20 may also include a heat source (not shown).The heat source may be used, for example, to catalyze or facilitate theexothermic reaction, such as by heating the solid waste before and/orduring mixing with oxidization agent 6. The heat source may also becapable of incinerating or sterilizing waste, for example if additionalincineration or sterilization is desired after the exothermic reactionis complete. The heat source may include, for example, a gas burner,laser heater, microwave heater, radiofrequency heater, electricresistance heater or the like. Heat transfer elements (e.g., metal rodsor plates) may be provided to contact or even pierce the waste toaccelerate heat transfer and water evaporation. In many embodiments,however, no heat source other than oxidizing agent 6 is needed, sincemixing the waste with oxidizing agent 6 is sufficient for wastetreatment needs.

In various alternative embodiments, waste treatment system 20 mayinclude fewer or larger numbers of components than described above. Forexample, any one of the components described above, or any combinationof components, may be provided in multiples (e.g., multiple holdingtanks 3, multiple liquid separators 4, etc.). In some embodiments, oneor more components may be removed from system 20. For example, in oneembodiment, holding tank(s) 3 may be eliminated, and liquid separator(s)4 may serve both as holding tanks and also as separators. In anotherexample, pump 22 may be part of system 20 in some embodiments and not inothers.

Referring now to FIG. 2, in another embodiment, a waste treatment system30 may be portable, for example for implementation and use on the backof a truck 36, such as the flatbed truck 36 pictured in FIG. 2. In thisembodiment, waste treatment system 30 includes a sewer collection hose31, a sewer pump 32, a holding tank 33, a mixing tank 35, and afertilizer outflow channel 38. Sewer hose 31 and sewer pump 32 may beused to channel sewage directly out of a sewer into holding tank 33.Sewage may then be mixed with an oxidizing agent, such as potassiumpermanganate, in mixing tank 35, which may be a screw operated mixingtank or any other suitable mixing tank, such as but not limited to theexamples listed above. Once waste is treated in mixing tank 35,resulting fertilizer may be diverted out of system 20 through fertilizeroutflow channel 38.

In alternative embodiments, waste treatment system 30 may include any ofa number of other configurations, combinations of components, sizes,shapes and the like, such as but not limited to one or more of thecomponents or aspects described above in relation to FIG. 1. Forexample, waste treatment system 30 may include a liquid separator and awater outflow channel for separating water from solid waste and allowingthe water to escape system 30. Additionally, system 30 may be sized tofit on any suitable truck or vehicle. Alternatively, waste treatment 30system may be installed above ground or below ground at a sewer site.

Although this invention has been disclosed in the context of certainembodiments and examples, the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and modifications and equivalents thereof.Thus, it is intended that the scope of the present invention hereindisclosed should not be limited by the particular disclosed embodimentsdescribed above.

What is claimed is:
 1. A waste treatment method, comprising: removingwater from solid waste in a liquid separator; transferring the solidwaste from the liquid separator to a mixing tank connected to the liquidseparator; transferring the water from the liquid separator to asanitizing tank; mixing the solid waste with an oxidizing agent in themixing tank to cause an exothermic reaction and convert the solid wasteto processed solid waste; collecting heat from the exothermic reactionin a heat exchanger coupled with the mixing tank; sanitizing the waterfrom the liquid separator in the sanitizing tank; channeling thesanitized water out of the sanitizing tank, detecting a problem in awaste treatment system used to perform the method; and diverting thewaste from a building sewer system into a public sewer system whereinthe method is performed by a waste treatment system located in or near acommercial or multiple-unit residential building.
 2. The method of claim1, further comprising, before separating the water from the solid waste:receiving waste from a building sewer system in at least one holdingtank; and channeling the waste from the at least one holding tank to theliquid separator.
 3. The method of claim 1, further comprising applyingthe heat from the heat exchanger to a source of domestic hot waterconnected to the heat exchanger.
 4. The method of claim 1, furthercomprising channeling the sanitized water into a water system for use astoilet water.
 5. The method of claim 1, further comprising collectingprocessed solid waste from the mixing tank in a collection tank.
 6. Themethod of claim 1, further comprising providing processed solid wastefrom the mixing tank for use as fertilizer.